This invention relates in general to optical transceivers and, more particularly, to laser rangefinders .
A laser rangefinder is an optical transceiver which is capable of measuring the distance between the rangefinder and a target in the distance. The laser rangefinder includes a laser light source or laser transmitter, and further includes a photodetector or laser receiver. Typically, the laser transmitter irradiates the target with incident laser light pulses and the laser receiver receives the reflected light pulses. A signal processor in the rangefinder records the time between transmission of a pulse by the laser transmitter and reception of the reflected pulse back at the rangefinder receiver. The signal processor then uses this time difference to calculate the distance between the rangefinder and the target.
In conventional laser rangefinders, great care must be taken to mechanically and optically align the laser transmitter and the laser receiver with respect to each other. That is, optical coupling in prior laser rangefinders was accomplished through the use of discrete coupling optics, namely lenses, which necessitated tight mechanical tolerancing of receivers and transmitters to maintain boresight and field of view (FOV) requirements. Additional fixed optics were also required to ensure power densities which did not exceed the damage threshold level of the photodetector in the laser receiver of the rangefinder. Moreover, with such rangefinders there was little flexibility in the placement of the laser receiver with respect to the laser transmitter.